A plug-in hybrid electric vehicle (PHEV) and an electric vehicle (EV) are mounted with an on-vehicle charger (for example, AC/DC converter) that can charge an on-vehicle high-voltage battery (DC side) from an electric power system (AC side). Meanwhile, expectations run high that the on-vehicle high-voltage battery is utilized as a home power source (V2H: vehicle to home) or as a buffer (V2G: vehicle to grid) for stabilizing the electric power system. This requires a bidirectional charger capable of bidirectionally converting electric power.
Such a bidirectional charger is provided with an AC-DC conversion circuit having a power factor correction (hereinafter referred to as PFC) function of converting AC to DC upon charging and an inverter function of converting DC to AC upon discharging, and a DC/DC converter.
Such a DC/DC converter has two single-phase bridge inverters and a transformer that isolates the single-phase bridge inverters. The single-phase bridge inverter has two series circuits connected in parallel, each series circuit having two switching elements connected in series (see Japanese Patent Application Laid-Open Publication No. 2012-196089).